ED69ray

With everyone building strokers now, just wondering who here is running a high rpm SB and whats your bore/stroke and cam/valvetrain combo.

Sure hyd roller strokers are great for having buckets of torque off idle...........but coming from the 4 cylinder bike world where power is made with short stroke and high rpm, I think I could appreciate a pushrod V-8 with a more dedicated powerband - say 3200 to 6800rpm.

302, 327, or 350 ? What have you guys run?

Gordonm

Mine has seen 7200 rpm and is a 385 ci. Plenty of big inch stroker SB and BB motors here running some high rpm. Built right they can rev pretty high. Not like the bike rpm you are talking about though. Some of those are insane rpms.

gkull

You build your motor to withstand 8000 rpm and then set your rev limiter at 7500 and it last allot longer.

I have several combos that have done 7500 near every day I drove them. Stoker cranks of 3.750, 3.875, 3.920 4.00 bores of 4.030 4.060 4.125 and 4.155 The ci sizes that I have build and used are 355, 358, 383, 391, 396, 408, 415, 421, 427, & 434

The 408 4 inch stroker 4.030 I would not recommend because I had to clearance grind the block so much that I ended up 1/2 filling the block water jackets with epoxy cement

My present Vette motor is 434 ci Motown small block. It could use shaft offset rockers, but I had to cut the costs because I had just broke the crankshaft when it was a 427 and less than a year old

ED69ray

It is insane.....its nothing today to get 160hp out of a 1 liter machine - liquid cooling allows stock CR's in the 12.5-1 range and light, ultra compact valvetrains allow powerbands into the 12k+ rpm range

Here's 1990 tech



A pretty simple air/oil cooled powerplant -

1157cc (70ci) bore 79mm x stroke 59mm
16 valve with o/h cams
powerband from 6000 to 9600rpm
max rpm 10,200
she made 121hp and 78tq on a chassis dyno


back to topic.........who's running a high rpm SB with a 3.0, 3.25 or 3.48 stroke?

gkull

Only dummies run 3.0, 3.25 or 3.48 strokes

v2racing

My 406 pulls hard past 7000 rpm. It probably saw past 7500 when it broke the tranny last week.

It's got a 4.155 bore and a 3.75 stroke. The rest of the discription is in my signature.

calwldlife

steel crank LT1 had 6500 tach
and the 327/350 also.

Budman68

327 bored and built to take at least 7000 rpm. Steel crank, HD Springs, and APR bolts. Lot's of oiling trick.

ED69ray

how did I know you were gonna say that

ED69ray

thats what I/m talking about. This inspired me:


"Chevrolet produced a special 302 cu in (4.9 L) engine for Trans Am racing from 1967-1969. It was the product of placing the 3-inch stroke crankshaft into a 4-inch bore block. Although the 283 also used a 3-inch stroke crankshaft, it was a low performance cast iron crankshaft. The crankshaft for the 302 was specially built of forged steel. This engine was used only in the first-generation Camaro Z28. Conservatively rated at 290 hp (216 kW), actual output was around 375 hp (280 kW). This block is one of 3 displacements that underwent a transformation for the 1968/1969 period when the main bearing size was increased from 2.30 in to 2.45 in.

A letter from G.D. Thompson, Chevrolet Engineering Laboratory, dated June 5, 1967 to D.A. Martens, Engineering Department, subject Z-28 Service Pack Power Breakdown states "engine capable of 448 HP will deliver 432HP in full vehicle dress" .... "as installed data corrected to 100 degree brake and 29.52hg dry barometer yields a maximum of 403.8 HP. This correction more closely represents what is available when installed in a vehicle" *bhp@7400rpm"


Sure its gonna have poor low end street manners and be a little hard on clutches..............but don't that sound like a fun motor to stomp on.

anyone with some real old school 302 numbers post up

What would a modern built 302, 327 be capable of in street trim and on todays pump gas?

Little Mouse

To get real power out of a say a 302 the word street trim would never apply or street gas when your talking NASP engine.

My first form of performace car was a new 69 Z/28. with a 254 .050 solid in it from the factory below 4000 rpm it would do nothing, to get any kind of power out of one like the bigger cube small blocks you would have to have a solid roller cam pulling in the 6500 rpm range to the moon range. I guess you could use intercooling put it under boost use pump gas and have some form of realistic street rpm band. There is no doubt oversquare engines are the best form of power, as an example I would much rather build a 305 engine using a 4.030 bore 3.0 stroke then build a 307 that used a 3.25 crank with the small 283 size bore, problem is with small blocks you can't go very big on bores, so you end up with long strokes. When your talking pushrod two valve engines they are low rpm, compaired to the multi valve overhead cam motorcycle engines, your putting up with pushrods that date back to the late 1800s two valves per cylinder that date back that far.

MotorHead

This is not the 60's, solid roller cams, shaft rockers all the modern close tolerance pieces out there you can and I did build a 427ci small block that will rev to 7500RPM + and there is plenty of power at under 2000RPM's that makes it a pleasure to cruise around town.

My buddy just got his chassis dyno fixed, I am out west right now but will put it on when I get back. I set my shift light to come on at 6000RPM and it comes on so fast I have no idea what I am actually shifting at but I know it's well above that when there's a bike behind me

bluzman2004

I know it isn't hard to hit my 7000 rpm rev limiter. Even with big bottom end torque (500ft/lb @ 3000 rpm & 575ft/lb @ 4500) good cylinder heads, valve train, and a solid roller cam have no problems to 7500 rpm.
434 sb 4.155 bore x 4 stroke.

Budman68

If we are thinking out of the box, what about a LSX 302 that will rev to 8000. That would be cool.

MotorHead

Yes it's not like the old days (oh yes I was there ), big inch small blocks with modern parts will run circles around anything from the past, and you don't need a short stroke to rev fast, like I said above my shift light comes on so fast I had to check it didn't get set lower by accident

My previous 406ci made 460 ft/lbs @ 2000RPM I can only imagine what the new setup is going to show

wytevette

The wife and I went to BIR for show and go last saturday, and there was a guy with a 69 camaro and he had a "427 big block", according to the announcer. When he snapped the throttle, and when he took off, the sound was incredible. It revved up like a screaming banshee and just sounded awesome. I don't remember his time, but it wasn't slow.

I am no engine tech wiz, and I have no idea what it will take to get there, but I am set on a 1970 vette with a aluminum 427.

v2racing

Chevy only built the 302 because that was the cubic inch the Trans Am class was limited to. It was basically a destroked 375 horse 327. Same cam and head with improved intake manifolds in both single and cross ram 4 barrels. If the class would have allowed 327 cubic inches there would have never been a 302.

As said before, there is no reason to build a small SBC anymore. All the parts are readily available to build large high revving small blocks.

Little Mouse

You could build a small cube small block with all the modern blocks, heads, valve trains, rev it to the moon but it would have no lower end need extreme compression, need ridicules gearing.

I watched jenkins 331 go across the scales at tulsa 1972 with him in it a little over 2500 pounds click off a 9.39 top qualifying time with old timey 4 speed trans, heads that are not as good as can be bought off a shelf today at dart or brodix, gear that puppy and go I guess.

The new motorcycles are really something just go down to the suzuki dealer pick one out with a high 9 second quarter 200 mph top end, do it for next to nothing what a car costs.

calwldlife

running a 350 with 11 to 1
steel crank
roller solids
ported heads
seen 7500
should go 8500

MotorHead

Was looking at a R1 the other day now that you mention it. It is all power to weight, a 3000lb Corvette with 650-700hp will blow by a stock R1 after about 150mph or so, there is a video on the net showing this fact. Bikes are fast but I know ( through the grapevine ) they aren't that fast